The Gemological Institute of America (GIA) has graded the largest polished blue synthetic diamond that the organization has ever examined. The emerald-cut, 5.03-carat HPHT Type-IIB stone was made by New Diamond Technology (NDT), based in St. Petersburg, Russia. The firm is one of the founding members of the International Grown Diamond Association which was launched earlier this month. The stone was inspected at the GIA's New York lab last month and received a fancy deep blue grade, according to a lab. The GIA published an exhaustive article on the stone's characteristics.